Multi-axis linear motor actuator

Abstract

A multi-axis linear motor actuator has a circuit board having a size covering coil portions in linear shaft motors arranged in a row, and combined with the linear shaft motors to be adjacent thereto and parallel to its arrangement direction; and magnetic shielding plates, longer than the coil portions, arranged and fixed along an axial direction at positions corresponding to positions between adjacent coil portions. Hall sensors are installed in the circuit board in each region corresponding to each linear shaft motor at intervals in a moving direction of a shaft of each linear shaft motor. Each magnetic shielding plate has a wide portion with a width greater than a diameter of the coil portion at a part corresponding to the region where the Hall sensors are installed. The circuit board has first slits for inserting the wide portions. The Hall sensors are installed adjacent to the wide portion.

The invention claimed is: 
     
       1. A multi-axis linear motor actuator comprising a plurality of linear shaft motors arranged in a row at a predetermined pitch, the linear shaft motors each comprising a magnet portion for the linear shaft motor and a coil portion for the linear shaft motor, the magnet portion including a plurality of permanent magnets which are connected to each other with the same magnetic poles faced to each other and which are fixed to a support member having a length equal to or longer than a total length of the plurality of permanent magnets connected to each other to form a shaft movable in an axial direction, the coil portion including a plurality of cylindrical coils connected to each other in a center axis direction and combined with the shaft to concentrically enclose the shaft via a gap so that the shaft is movable with respect to the axial direction, the multi-axis linear motor actuator including:
 a circuit board which has a size sufficient to cover a plurality of the coil portions in the plurality of linear shaft motors arranged in a row and which is combined with the plurality of linear shaft motors so as to be adjacent thereto and parallel to an arrangement direction of the plurality of linear shaft motors; and 
 a plurality of magnetic shielding plates, longer than the coil portion, each arranged and fixed along the axial direction at least at a position corresponding to a position between adjacent ones of the plurality of coil portions arranged in a row; and 
 a pair of Hall sensors installed in the circuit board in each of regions corresponding to the shafts, same in number as the plurality of linear shaft motors, at intervals in a moving direction of the shaft; 
 each of the magnetic shielding plates having a wide portion with a width greater than a diameter of the coil portion at least at a part corresponding to the region where the pair of Hall sensors are installed; 
 the circuit board being provided with a plurality of first slits each for inserting the wide portion; 
 the pair of Hall sensors being installed adjacent to the wide portion of the magnetic shielding plate. 
 
     
     
       2. The multi-axis linear motor actuator according to  claim 1 , wherein:
 the pair of Hall sensors are installed on a surface of the circuit board that is opposite to another surface faced to the coil portion; and 
 an interval between the pair of Hall sensors is set so as to correspond to an electrical angle of 90 degrees of a sine waveform of a surface magnetic flux density of the magnet portion. 
 
     
     
       3. The multi-axis linear motor actuator according to  claim 1 , further comprising:
 a coil fixing member having a receiving portion in which the plurality of coil portions in the plurality of linear shaft motors are fixed in a state of being arranged in a row at the predetermined pitch; 
 the circuit board being attached to the receiving portion of the coil fixing member. 
 
     
     
       4. The multi-axis linear motor actuator according to  claim 2 , further comprising:
 a coil fixing member having a receiving portion in which the plurality of coil portions in the plurality of linear shaft motors are fixed in a state of being arranged in a row at the predetermined pitch; 
 the circuit board being attached to the receiving portion of the coil fixing member.